TELUS indicates that Netflix HD will consume approx 3GB per hour on this page. That seems about twice what it should be.
Netflix indicates TELUS DSL to be about 3.38Mbps for HD. So 3.38Mbs x 3600s/hour = 1.52GB per hour.
I haven't checked my own actual rate, so will have to see, but 3GB/h seems high for estimating what your Netflix data usage should be.
It's likely just an estimate. You can easily adjust the video quality on Netflix's site anyways.
So I found on Netflix the "example short" that indicates the actual data rate. With 1080p it indicates that I am receiving 5888kbps, which works out to about 2.5GB/h. So TELUS estimate of 3GB/h is about right, assuming that you have selected the 1080p option on you Netflix account. Mine had defaulted to 720p, which would result in about 1.5 GB/h.